1. Field of the Invention
The present invention relates to a video processing method and system. More particularly, the present invention relates to a video processing method and system, in which encoding bit rates of source image frames from an image sequence are checked against a bandwidth of a network which may vary, and changed as needed when it is determined that any of the encoding bit rates exceed said bandwidth.
2. Description of the Related Art
FIG. 1 shows the basic layout of a conventional video processing system. As an example, the conventional video processing system may be a videoconference system. In the conventional video processing system, a plurality of source image frames 9011˜901n included in a real-time image sequence are compressed into video signals by a video encoder 91. The video signals are then transmitted via a network 8 to a video decoder 92. The video decoder 92 decodes the video signals for recovery into a series of output image frames 9021˜902n. 
In the conventional video processing system, the entire process from inputting the source image frames 9011˜901n into the video encoder 91 to transmitting the resulting signals via the network 8 for output to the video decoder 92 is conducted using a single fixed resolution. Therefore, if the bandwidth of the network 8 is abruptly reduced by a significant amount, and the encoding bit rate (data amount of each frame×frame rate) exceeds the bandwidth, this will result in intermittent and/or unclear pictures at the receiving end.
One approach used in the conventional video processing system to overcome the above problem is that in which the resolution of the source image frames 9011˜901n is initially set sufficiently low so that any unexpected drop in the bandwidth of the network 8 will not result in an encoding bit rate that exceeds the bandwidth. However, such an approach is not ideal since the resulting output image frames 9021˜902n will be of a low quality.
According to another conventional approach, bandwidth detection is performed prior to operation of the video processing system, after which the resolution to be employed by the video encoder 91 is determined based on the detected bandwidth. However, no further adjustment in resolution is possible with the use of such an approach. This may be quite problematic in situations where the bandwidth detected prior to operation of the video processing system is not representative of the typical bandwidth of the network 8.
According to yet another conventional approach, operation of the video processing system is discontinued and the resolution is reset, after which the system is restarted. In the case where the video processing system is a videoconference system, such a pause in operation is not the best way to remedy problems encountered in a system operating in real-time.